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feat(library/simplifier): we can "rewrite" with transitive relations

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The simplifier does not really need the relation to be an equivalence.
Transitivity is the main required property (we need to chain rewrites
together).
This commit is contained in:
Leonardo de Moura 2015-07-12 14:24:05 -04:00
parent f8d472c9f1
commit 3cb8568fb5
3 changed files with 11 additions and 11 deletions
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18
src/library/simplifier/ceqv.cpp
View file

@ -31,10 +31,10 @@ class to_ceqvs_fn {
return is_sort(m_tc.whnf(m_tc.infer(e).first).first);
}
bool is_equivalence(expr const & e) {
bool is_transitive(expr const & e) {
if (!is_app(e)) return false;
expr const & fn = get_app_fn(e);
return is_constant(fn) && ::lean::is_equivalence(m_env, const_name(fn)) && is_type(e);
return is_constant(fn) && ::lean::is_trans_relation(m_env, const_name(fn)) && is_type(e);
}
list<expr_pair> lift(expr const & local, list<expr_pair> const & l) {
@ -46,7 +46,7 @@ class to_ceqvs_fn {
list<expr_pair> apply(expr const & e, expr const & H) {
expr c, Hdec, A, arg1, arg2;
if (is_equivalence(e)) {
if (is_transitive(e)) {
return mk_singleton(e, H);
} else if (is_standard(m_env) && is_not(m_env, e, arg1)) {
expr new_e = mk_iff(e, mk_false());
@ -110,10 +110,10 @@ list<expr_pair> to_ceqvs(type_checker & tc, expr const & e, expr const & H) {
return to_ceqvs_fn(tc)(e, H);
}
bool is_equivalence(environment const & env, expr const & e, expr & rel, expr & lhs, expr & rhs) {
bool is_transitive(environment const & env, expr const & e, expr & rel, expr & lhs, expr & rhs) {
buffer<expr> args;
rel = get_app_args(e, args);
if (!is_constant(rel) || !is_equivalence(env, const_name(rel)))
if (!is_constant(rel) || !is_trans_relation(env, const_name(rel)))
return false;
relation_info const * rel_info = get_relation_info(env, const_name(rel));
if (!rel_info || rel_info->get_lhs_pos() >= args.size() || rel_info->get_rhs_pos() >= args.size())
@ -123,9 +123,9 @@ bool is_equivalence(environment const & env, expr const & e, expr & rel, expr &
return true;
}
bool is_equivalence(environment const & env, expr const & e, expr & lhs, expr & rhs) {
bool is_transitive(environment const & env, expr const & e, expr & lhs, expr & rhs) {
expr rel;
return is_equivalence(env, e, rel, lhs, rhs);
return is_transitive(env, e, rel, lhs, rhs);
}
bool is_ceqv(type_checker & tc, expr e) {
@ -167,7 +167,7 @@ bool is_ceqv(type_checker & tc, expr e) {
e = instantiate(binding_body(e), local);
}
expr lhs, rhs;
if (!is_equivalence(env, e, lhs, rhs))
if (!is_transitive(env, e, lhs, rhs))
return false;
// traverse lhs, and remove found variables from to_find
for_each(lhs, visitor_fn);
@ -230,7 +230,7 @@ bool is_permutation_ceqv(environment const & env, expr e) {
num_args++;
}
expr lhs, rhs;
if (is_equivalence(env, e, lhs, rhs)) {
if (is_transitive(env, e, lhs, rhs)) {
buffer<optional<unsigned>> permutation;
permutation.resize(num_args);
return is_permutation(lhs, rhs, 0, permutation);

2
src/library/simplifier/ceqv.h
View file

@ -8,7 +8,7 @@ Author: Leonardo de Moura
#include "kernel/type_checker.h"
namespace lean {
bool is_equivalence(environment const & env, expr const & e, expr & rel, expr & lhs, expr & rhs);
bool is_transitive(environment const & env, expr const & e, expr & rel, expr & lhs, expr & rhs);
/** \brief Given (H : e), return a list of (h_i : e_i) where e_i can be viewed as
a "conditional" rewriting rule. Any equivalence relation registered using
the relation_manager is considered.

2
src/library/simplifier/rewrite_rule_set.cpp
View file

@ -117,7 +117,7 @@ rewrite_rule_sets add_core(type_checker & tc, rewrite_rule_sets const & s,
new_e = instantiate(binding_body(new_e), mvar);
}
expr rel, lhs, rhs;
if (is_equivalence(env, new_e, rel, lhs, rhs) && is_constant(rel)) {
if (is_transitive(env, new_e, rel, lhs, rhs) && is_constant(rel)) {
new_s.insert(const_name(rel), rewrite_rule(id, univ_metas, to_list(metas), lhs, rhs, new_h, is_perm));
}
}